1. Field of the Invention
Embodiments of the invention relate to a touch screen, and more particularly, to a touch screen driver for dividedly driving a touch screen.
2. Discussion of the Related Art
User interface (UI) is configured so that people (users) can easily control various electronic devices as they desire. Examples of the user interface include a keypad, a keyboard, a mouse, an on-screen display (OSD), and a remote controller having an infrared communication function or a radio frequency (RF) communication function. User interface technologies have continuously expanded to increase user's sensibility and handling convenience. The user interface has been recently developed to include touch UI, voice recognition UI, 3D UI, etc.
The touch UI has been necessarily used in portable information appliances. The touch UI has been implemented by a method for forming a touch screen on the screen of a display device.
A mutual capacitance touch screen includes Tx lines, Rx lines crossing the Tx lines, and touch sensors formed at crossings of the Tx lines and the Rx lines. Each of the touch sensors has a mutual capacitance.
A touch screen driver for driving the mutual capacitance touch screen supplies a driving signal to the Tx lines, and receives charges of the touch sensors through the Rx lines. The touch screen driver senses changes in voltages charged to the touch sensors before and after a touch operation to decide whether or not a conductive material touches the touch screen and to decide a touch position when the conductive material touches the touch screen. The touch screen driver is integrated into an integrated circuit called a readout integrated circuit (ROIC) and is connected to the touch screen.
In general, one integrated circuit is connected to one touch screen. The integrated circuit includes a Tx channel module, which is connected to the Tx lines and supplies the driving signal to the Tx lines, and an Rx channel module, which is connected to the Rx lines and receives charges of the touch sensors through the Rx lines. The integrated circuit has to include Tx channels equal to or greater than the number of Tx lines in the touch screen and Rx channels equal to or greater than the number of Rx lines in the touch screen, so as to sense all of the touch sensors of the touch screen.
When a resolution and the size of the touch screen increase, the number of Tx channels and the number of Rx channels of the touch screen increase. Thus, a new integrated circuit capable of accepting an increase in the resolution and the size of the touch screen increase has to be developed.